//RealSubject
struct Image {
    file_name: String
}
impl Image {
    fn draw(&self) {
        println!("draw {}", self.file_name);
    } 
}

//Proxy
struct ImageProxy {
    file_name: String,
    image: Option<Image>
}
impl ImageProxy {
    fn get_image(&mut self) -> Option<&Image> {
        if self.image.is_none() {
            self.image = Some(Image {
                    file_name: self.file_name.clone()
            });
        }
        self.image.as_ref()
    }

    fn get_file_name(&self) -> String {
        self.file_name.clone()
    }

    fn draw(&mut self) {
        let image: &Image = self.get_image().unwrap();
        image.draw();
    } 
}

//Client
let mut proxy = ImageProxy{ 
    file_name: String::from("1.png"),
    image: None };
//operation without creating a RealSubject
let file_name = proxy.get_file_name();
println!("file_name is {file_name}");

//forwarded to the RealSubject
proxy.draw();